Firstly, speed. Opening that mailbox with a GUI-based email application on a developer desktop was orders of magnitude slower, if it opened at all. The volume was just far more than most desktop email apps was used to at the time.

Secondly, it's unix, so you're operating a tool that allows you to construct ad-hoc workflows very quickly. There was a scoring bug where the stats software (literally a pipe-delimited text file that was updated by midnight the day of the game) had given a safety to the wrong player with the same name. I had hundreds of emails complaining about this bug, and I needed to fix it. I can search in Pine, find a result set (ie. everyone who mentioned this players unique name), compose an email to all of them (BCCd), and pull in a text file as the email body that I'd written previously, that explained how and when this would be fixed.

I had TONS of canned email responses, saved as text files, so finding a set of emails, and sending replies w/ the contents from a saved text file, was a very routine workflow that happened dozens of times a day for various situations.

I knew nothing about american football really, but with perl and pine, I felt like there was nothing I couldn't do.